The present invention generally relates to generator control systems and more particularly, to aircraft voltage regulators.
It is known for generator control systems in aircraft to implement software-based digital control mechanisms like RMS voltage control, compensation for PMG voltage in variable frequency systems.
Referring to FIG. 1, a prior art configuration illustrates a typical software-based voltage control using a digital voltage regulation system 110. As shown in FIG. 1, analog control feedback signals 105 are conditioned in a signal conditioning unit 111 and converted to digital in an analog to digital converter 112. The feedback signals 105 may then be fed to a digital control 115 for compensation control. The control algorithm that may be used varies depending on the application and desired effectiveness of control. Based on the control algorithm, the digital processor 119 commands the digital control 115 to generate a gating signal to a gate driver 135 and a field modulation switch 137 to perform pulse width modulation (PWM) on the generator excitation voltage supply. Therefore the generator field excitation current is adjusted dynamically to minimize the voltage variation at the point of regulation at different operating conditions.
In some cases software-based control using digital voltage regulation may be susceptible to Single/Multiple Event Upsets (SEU) and indirect effects from lightning. Such effects may cause a microprocessor or digital signal processor 119 to reset or stop functioning. During this time, all devices connected to the power system may temporarily shutdown and require a few seconds to get back into the original operating state. These types of events could incur serious workload issues for the aircraft electrical power systems and potentially have dangerous results for pilots flying the aircraft.
As can be seen, there is a need for a generator regulator system that can function during temporary interruption of regulation.